I (re-)discovered PROLOG only a few months ago after having learned it superficially in the 90's. Then I wanted my own, hackable interpreter, and started to read books about PROLOG implementation. I found them to be too complex for my needs, so I finally sat down and asked myself "If I were a PROLOG interpreter, what would I do?" Then those six slides materialized in my head.

In the meantime, I have written an interpreter that is mostly compatible to DEC-10 PROLOG, have read Clocksin, Boizumault, and half of O'Keefe (and skimmed through a few others), and I am quite enjoying the tour so far! PROLOG is a fascinating language, and there are so many things to discover!